As known in the state of the art, free draws have been used in paper machines when passing a paper web from one treatment stage to the next. The general trend today is that attempts are being made to pass the paper web as supported from one treatment stage to the next, and the development has indeed moved forward so that the wet end and the dryer section of the paper machine have for the most part been provided with means so that the transfer of paper is supported over the entire distance. However, in finishing there are stages in which unsupported runs of the web are still used at present, for example, in connection with calenders or on-line coating devices. Since the current trend is also that finishing devices are connected as on-line units to the paper machine, the significance of web support matters for the efficiency of the total line is greater than before when using off-line further treatment units. Since all unit process devices are in the same chain, the problems presented by free draws in the transfer of the web and possible web breaks cause problems to the entire line and may cause even a shutdown of the entire line.
Today's paper machines also aim at an increase of speed and decrease of the basis weight of the paper web as well as at higher efficiency requirements. Thus, unsupported runs cause problems, and therefore their elimination is very important.
Thus, it is an object of the invention to provide a method and a device in connection with which the run of the web is supported in connection with a finishing device.
With respect to the state of the art associated with the invention, reference is made to FI patent application 973725 which discloses an arrangement in which a web is conveyed by means of a support wire or equivalent to a multi-nip calender from the last drying cylinders placed substantially higher than the other cylinders of a dryer section, on which support wire the web is passed to the first pre-nip of the calender formed between the topmost calender roll and a belt calender roll or a wire guide roll.
An arrangement is known from the state of the art in which a paper web is passed as a supported run through a calender supported by a support member which has been guided to run through a calendering nip of the calender. In this respect, reference is made to FI patent 95 061. A problem in this prior-art arrangement is that the support member of paper influences the process itself and thus also the quality of the paper being manufactured as the support member runs through the nip. Further, this restricts the selection of the support member material to be used because the support member thus takes part in the process, which means that the material of the support member shall be selected according to the demands of the process and the process parameters shall be adjusted taking account of the effect of the support member.